1. Field of the Invention
The technology disclosed relates to a test platform for testing radio communications in a MIMO (multiple-input multiple-output) RF (radio frequency) environment, and more particularly to techniques for phase calibration among multiple signal paths in the test platform.
2. Description of Related Art
In a test platform for testing radio communications in a MIMO RF environment, a multi-path radio channel can be emulated in a channel emulator as multiple delayed copies of a signal transmitted from a signal source, and through multiple signal paths within the test equipment. The test platform needs to ensure that the combined copies of the signal represent the desired test condition. A test platform includes multiple pieces of testing equipment. Because of the connections between pieces of testing equipment and electrical characteristics of each piece of equipment, including relative phase relationships between different components within a piece of testing equipment, there can be phase misalignment between signals throughout the signal paths in the test platform.
An opportunity arises to provide a method of calibrating a test platform to establish a phase relationship between signals reaching a measurement location from multiple signal paths.